R Grep变量的文件名

I am new to R so I am struggling with what I imagine is a fairly simple question. For this question I am not looking for someone to give me just a solution. I was hoping that someone could explain the answer to me, so that I might learn to do it myself, rather than just copy what it is you have done. That being said, here is my problem and questions.I am new to R so I am struggling with what I im